In recent years, demand for thin displays mainly applied to TVs, PC monitors, mobile terminals, and the like have increased rapidly and further development has been promoted. The thin displays include a liquid crystal display device (LCD) and a display device equipped with a light-emitting element. In particular, an active matrix display using a light-emitting element is expected as a next-generation display for its features of high response speed, wide viewing angle, and the like in addition to advantages of a conventional LCD such as thinness, lightness in weight, and high image quality.
In an active matrix display using a light-emitting element, a structure shown in FIG. 17A is given as the most basic pixel structure (see Non-Patent Document 1: M. Mizukami, K. Inukai, H. Yamagata, et al., SID '00 Digest, vol. 31, pp. 912-915). In FIG. 17A, each pixel has a driver transistor 202 for controlling current supply to a light-emitting element 204, a switch transistor 201 for taking a potential of a data line 206 into a gate node G of the driver transistor 202 by a scan line 205, and a holding capacitor 203 for holding the potential of the node G.